1. Field of the Invention
The present invention relates to devices for scrubbing toxic gases which flow from a gas leak on, for example, a gas cylinder or a gas flow pipe. In particular, the present invention relates to portable, self-contained emergency response devices for gas leakage containment and scrubbing which are useful for temporarily controlling and containing gas leaks during emergency situations.
2. Description of the Prior Art
The extensive use of toxic and corrosive gases in industry has led to problems which occur upon leakage of gases in storage or flow system devices. In the case of gas cylinders, increasing government regulations on the handling of gas cylinders has occurred, with a special emphasis on emergency situations such as leaks from the head or valve of such a cylinder. The use of toxic and corrosive gases in the chemical and semiconductor industries has led to similar types of regulations for gas cylinders and flow systems.
Recently, emphasis has been placed on developing preplans to deal with emergency situations involving these gas cylinder or flow systems, leading to efforts in the industry to develop procedures and equipment to control a leakage problem if one should occur. A number of devices have been developed for use in controlling leaks of toxic or corrosive gases.
For example, in U.S. Pat. No. 5,086,804 to Ngai, an emergency security device for the head of a leaking gas cylinder is provided. In Ngai, a cap is equipped with a threaded collar adapted to be tightly engaged onto a screw thread provided on the head of a leaking cylinder. A sealing ring is disposed in the cap to provide an airtight seal between the cap and the cylinder after engagement with the screw thread. An inlet port in the cap allows for feeding an inert purge gas into the cap and an outlet port is connected to a scrubbing material which irreversibly reacts with the leaking gas.
In U.S. Pat. No. 4,625,627 to Livanos, a ventilated cabinet for containing gas supply vessels is provided. In Livanos, a gas cabinet for enclosing one or more compressed gas cylinders is ventilated for rapid removal of any gas leaked from the cylinders. The cabinet has a perforated plate as its floor which is used as an air inlet to allow airflow through the interior of the cabinet. A tapered roof has an exhaust port which may be connected to a plant ventilation system for removing the exhausted air from the cabinet.
U.S. Pat. No. 4,494,666 illustrates a device wherein the leaking gas cylinder is completely introduced into a high pressure containment vessel which is then transported to a safe area for disposal. However, these vessels are expensive and for larger cylinders they are heavy and cumbersome.
U.S. Pat. No. 3,976,050 illustrates a device for absorbing exhaled radioactive gases using a radioactive xenon gas trap and an activated carbon adsorbent. Absorbent filled containers are connected in series so that the absorbent solids in each container are completely out of contact with each other.
A chlorine kit "A" contains a pressure cap assembly which can seal the valve assembly of a chlorine cylinder with the use of a set of chains connected to the base of the cylinder. Such a device is effective but limited to low vapor gases, such as sulfur dioxide or chlorine. It is not generally useful for gases such as arsine or hydrogen chloride.
None of the patents and devices described above provides the important advantages of a portable and self-contained leakage containment and scrubbing means which is easily used for on-site scrubbing of a variety of toxic or corrosive gases. Moreover, none of the patents and devices described above provides the capability to such a portable and self-contained device to scrub a variety of toxic or corrosive gases in an atmosphere which limits the danger of explosion.